WATERPROOFING

One of the major technical achievements the iBotics team has made is the development of our in-house waterproofing techniques.

Motors & Servos

Every one of the motors that actuate the Stingray is waterproofed using techniques developed by the iBotics team.

There are a total of five DC brushless motors on the Stingray:
three vertical thrusters and two that drive the Voith-Schneider
propellers. The waterproofing procedure used on these motors involves
disassembling each motor to apply a specialized conformal coating to the
stator windings. The leads to the motor are connected to a Teledyne
Interconnect wet-mateable submersible cable at the source using a
special thermal-epoxy core heat shrink tubing. This particular method of
waterproofed motors is another signature element of the Stingray that
has taken three years to perfect; the original batch of waterproof
motors lasted for only a few weeks before failing, and the batch
currently installed on the Stingray have been going strong for over six
months. The techniques developed by iBotics provide the Stingray with
powerful, reliable, small-profile actuators that are staggeringly
inexpensive.

The Stingray is also equipped with two pairs of Futaba high-torque
servo motors that control each of the Voith-Schneider propellers. The
servos are waterproofed by encasing the servos in a flexible latex
casing, exchanging the air in the casing with mineral oil, and then
sealing the casing around the armature of the servo. Similar to the
technique used for the brushless motors, our custom in-house servo
water-proofing technique provides the Stingray with low-cost actuation
without sacrificing performance.

Switches

To operate the Stingray autonomously, there are two control switches:
the computer power switch, and the kill switch. Both of these switches
are potted in epoxy and operated magnetically.

The computer switch is housed in the front of the Stingray and is
controlled by a 3-D printed mini-Stingray key. Waving the key in front
of this switch starts up the main computer and its peripherals. Holding
the key on the switch for several seconds causes the Stingray to safely
shut down.

The kill switch is housed in the base of the Stingrayâ€™s tail.
When the operating magnet is connected to the switch, power is provided
to all of the propulsion systems; and when the magnet is removed, the
propulsion systems are not powered.

Tether

The Stingray can be connected to a wireless
buoy through a submersible tether for remote operation and testing. The
tether is built from an Xtreme-Green Cat-5e Ethernet cable donated by
Ocean Innovations. The tether is easily connected or disconnected by the
operator due to the Subconn wet-mateable connector spliced to the
tether.